In conventional chemical reactors, the reaction chamber containing the catalyst has straight walls in the direction of the flow. Thus, the reaction chamber forms a channel that has a constant cross-section along the flow direction over the length of the chamber between an inlet and an outlet. The conventional reactors described here include flow through type catalytic and non-catalytic reactors. Catalytic reactions are either heterogeneous or homogeneous.
Straight channel reactors have several drawbacks. For non-zero order homogeneous or heterogeneous reactions, temperature varies considerably from point to point in the catalyst bed, in particular for highly exothermic or endothermic chemical reactions. Temperature lacks uniformity in the axial direction (flow direction) and reactant concentrations are typically high in the inlet zone. As a result, the integrated effects can cause high reaction rates in the inlet zone for highly exothermic reactions, as well as local hot spots, resulting in fast catalyst deactivation and low selectivity of desired products. On the other hand, for endothermic reactions, this can cause cold spots and poorer catalyst utilization.